What was the trade of Demetrius, who stirred up a riot against Paul in Ephesus?

Answer: Silversmith

Demetrius, a silversmith who made silver shrines of the goddess, feared Paul's preaching would ruin the craftsmen's business.

“It began with a silversmith named Demetrius who made silver shrines of Artemis, bringing much business to the craftsmen.”— Acts 19:24 (BSB)